Machine Body and Working Machine

ABSTRACT

An injector injects urea water as a liquid reducing agent; a NOx sensor detects concentration of nitrogen oxide in exhaust gas; and an air duct including an inlet side opening and outlet side opening cools at least either one of urea water in urea water hose, NOx sensor or injector with cooling air introduced from outside of the machine room. A ventilation opening at the outside of the machine room communicates with the inlet side opening of the air duct using negative pressure formed in a circumference of exhaust gas flow by an ejector arranged in an exhaust pipe passage.

TECHNICAL FIELD

The present invention relates to a machine body and a working machine both characterized by a cooling structure for an exhaust gas cleaning apparatus.

BACKGROUND ART

An exhaust gas cleaning apparatus for a diesel engine includes an injector that injects a reducing agent (DEF: Diesel Exhaust Fluid; a urea aqueous solution, in general) and a nitrogen oxide sensor (NOx sensor).

In general, the exhaust gas cleaning apparatus is installed in an exhaust line. Hot exhaust gas flows through the exhaust line, and thus, the exhaust line and the exhaust gas cleaning apparatus become hot.

When the exhaust gas cleaning apparatus is hot, the injector and NOx sensor installed in the exhaust gas cleaning apparatus are also exposed to elevated temperatures. Moreover, a reducing agent supply pipe (in general, a urea aqueous solution hose) through which the reducing agent is supplied to the injector is partly exposed to elevated temperatures. When the urea aqueous hose, the NOx sensor, or the injector is exposed to elevated temperatures for a long time, the durability thereof may be impaired for structural reasons, and the temperature of the urea aqueous solution in the urea aqueous solution hose rises to affect the reducing effect of the urea aqueous solution.

In a traveling vehicle such as a car, the injector may be cooled when exposed to outside air during traveling or when a cool reducing agent flows into the injector, but cooling performance may still be insufficient. For such a case, a technique has been proposed which involves circular feeding of a refrigerant such as cooling water to the injector (see, for example, Patent Document 1).

Another technique has been proposed which involves introduction of cooling air throughout a housing chamber for the exhaust gas cleaning apparatus based on an ejector effect for engine exhaust gas (see, for example, Patent Document 2).

Patent Document 1: Japanese Patent Application Laid-Open No. H9-96212

Patent Document 2: Japanese Patent Application Laid-Open No. 2003-41627

Patent Document 1 needs a dedicated cooling water circuit through which a refrigerant such as cooling water flows around the periphery of the injector. Such a cooling water circuit is a large-scale, expensive cooling apparatus.

Patent Document 2 uses the structure in which cooling air is introduced throughout the housing chamber for the exhaust gas cleaning apparatus, and thus needs a large-scale isolation chamber. This disadvantageously leads to the need for a large installation space.

With these problems in view, it is an object of the present invention to provide a machine body and a working machine which need only low costs and a small space and which allow a desired portion of an exhaust gas cleaning apparatus to be solely cooled.

DISCLOSURE OF THE INVENTION

An invention set forth in claim 1 is a machine body including a machine room, an engine installed in the machine room, an exhaust line through which exhaust gas from the engine is discharged, an exhaust gas cleaning apparatus provided in the exhaust line to execute a reducing process on nitrogen oxide in exhaust gas, and a reducing agent supply apparatus that supplies a liquid reducing agent to the exhaust gas cleaning apparatus through a reducing agent supply pipe, wherein the exhaust gas cleaning apparatus includes an injector that injects the liquid reducing agent supplied by the reducing agent supply apparatus through the reducing agent supply pipe, a nitrogen oxide sensor that detects a concentration of the nitrogen oxide in the exhaust gas, an air passage body installed so as to surround at least one of a part of the reducing agent supply pipe, a part of the nitrogen oxide sensor, and a part of the injector to allow at least one of the liquid reducing agent in the reducing agent supply pipe, the nitrogen oxide sensor, and the injector to be cooled using cooling air taken from an outside of the machine room, the air passage body including an inlet side opening and an outlet side opening, an outside air intake port which communicates with the inlet side opening of the air passage body and which opens to the outside of the machine room, and an ejector provided in the exhaust line to forcibly discharge air in the air passage body through the outlet side opening of the air passage body by utilizing a negative pressure formed around an exhaust gas flow.

An invention set forth in claim 2 is a working machine including the machine body set forth in claim 1 and a working apparatus mounted on the machine body.

The invention set forth in claim 1 provides the structure in which the inlet side opening of the air passage body is in communication with the outside air intake port outside the machine room and in which the ejector provided in the exhaust line utilizes the negative pressure formed around the exhaust gas flow to suck the air in the air passage body into the exhaust gas flow in the exhaust gas line through the outlet side opening of the air passage body, allowing the air to be forcibly discharged. Thus, while the engine is being driven to discharge the exhaust gas, the outside air is constantly introduced into the air passage body to enable efficient cooling of at least one of the liquid reducing agent in the reducing agent supply pipe, the nitrogen oxide sensor, and the injector. Thus, a cooling effect can be exerted using a low-cost duct structure without the need for a special cooling water line or pump. Furthermore, the air passage body may be installed which locally surrounds the cooling target area, allowing space to be conserved.

The invention set forth in claim 2 can provide inexpensive cooling means for a working machine that performs operations at a fixed location, the cooling means allowing efficient cooling of at least one of the liquid reducing agent in the reducing agent supply pipe, the nitrogen oxide sensor, and the injector.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic plan view showing an embodiment of a machine room in a machine body according to the present invention.

FIG. 2 is a perspective view showing an exhaust gas cleaning apparatus in the machine body and a peripheral portion of the exhaust gas cleaning apparatus.

FIG. 3 is a perspective view showing only the peripheral portion of the exhaust gas cleaning apparatus in the machine body.

FIG. 4 is a front view showing a working machine including the machine body.

BEST MODE FOR CARRYING OUT THE INVENTION

The present invention will be described below based on an embodiment shown in FIGS. 1 to 4.

As shown in FIG. 4, a working machine 10 like a hydraulic excavator has a machine body 11 including a lower traveling body 12 and an upper slewing body 13 mounted on the lower traveling body 12 so as to be able to slew. A working apparatus 14 like a bucket is mounted on the upper slewing body 13 of the machine body 11.

On the upper slewing body 13, a cab 15 in which an operator's seat is provided and a storage box 16 with tools and the like housed therein are provided across an area where the working apparatus 14 is mounted. A fuel tank 17 and a hydraulic oil tank 18 are provided behind the storage box 16. A machine room (engine room) 19 is installed on the upper slewing body 13 behind a slewing bearing portion. A counterweight 20 is further installed behind the machine room 19.

As shown in FIG. 1, an engine 21 is installed in the machine room 19. A cooling fan 21 f is located on one side of the engine 21 to blow cooling air sucked from the outside against a cooling package including a radiator, an oil cooler and the like (not shown in the drawings) to cool the cooling package. An exhaust gas cleaning apparatus 22 is located on the other side of the engine 21 to execute an exhaust gas cleaning process on an exhaust system for the engine 21.

As seen back in FIG. 4, an engine hood 23 is provided at the top of the machine room 19 so as to be openable and closable. A tip of an exhaust line 24 through which exhaust gas from the engine 21 is discharged projects from the engine hood 23. Furthermore, a side door 25 is provided on an outer side surface side of the machine room 19 so as to be openable and closable. A ventilation port 26 serving as an outside air intake port is formed in an upper portion of the side door 25 and is open to the outside of the machine room 19.

As shown in FIG. 1 and FIG. 2, in the exhaust gas cleaning apparatus 22, an exhaust opening of the engine 21 is connected, via connection means 21 e serving as a start point for the exhaust line 24, to an end portion 27 a of a black exhaust removal apparatus (diesel particulate filter) 27 that removes black exhaust contained in exhaust gas discharged from the engine 21. A pipe connection portion 27 b provided at an opposite end portion of the end portion 27 a of the black exhaust removal apparatus 27 is connected, via a pipe 28 a, to an opposite end portion 28 b of a nitrogen oxide reduction apparatus (selective catalytic reduction) 28 that executes a reduction process on nitrogen oxide in exhaust gas. The remaining portion of the exhaust line 24 is connected to a pipe connection portion 28 c provided at an end portion of the nitrogen oxide reduction apparatus 28 which is opposite to the opposite end portion 28 b.

An injector 29 is attached to the pipe connection portion 27 b of the black exhaust removal apparatus 27 to inject a liquid reducing agent such as a urea aqueous solution toward the pipe 28 a, via which the black exhaust removal apparatus 27 and the nitrogen oxide reduction apparatus 28 are in communication with each other. An NOx sensor 30 is located near the injector 29 and serves as a nitrogen oxide sensor that detects the concentration of nitrogen oxide (NOx) in exhaust gas.

The NOx sensor 30 includes an upstream side NOx sensor main body 30 a provided in the pipe connection portion 27 b of the black exhaust removal apparatus 27, a downstream side NOx sensor main body 30 b provided in the pipe connection portion 28 c of the nitrogen oxide reduction apparatus 28, a control box 30A connected to the upstream side NOx sensor main body 30 a, and a control box 30B connected to the downstream side NOx sensor main body 30 b.

A reducing agent supply apparatus 31, which feeds a liquid reducing agent such as a urea aqueous solution from the inside of the storage box 16 located at a position not thermally affected by the engine 21 as shown in FIG. 4 to the nitrogen oxide reduction apparatus 28, is provided with respect to the injector 29.

As shown in FIG. 4, the reducing agent supply apparatus 31 includes a liquid reducing agent tank 32 installed in the storage box 16 and in which the liquid reducing agent is stored and a liquid reducing agent pump 33 serving as a liquid reducing agent supply source that pumps up and ejects the liquid reducing agent in the liquid reducing agent tank 32, and a urea aqueous solution hose 34 serving as a reducing agent supply pipe and disposed to extend from the liquid reducing agent pump 33 through a piping path in the machine body 11 to the injector 29 for injection of the liquid reducing agent. An air passage body 35 is provided so as to surround a part of a tip of the urea aqueous solution hose 34.

As shown in FIG. 1, the following are housed inside the air passage body 35: a part of the injector 29, a part of the NOx sensor 30, and a part of the urea aqueous solution hose 34 in which the urea aqueous solution in the urea aqueous solution hose 34 serving as a liquid reducing agent is likely to be thermally affected by the exhaust gas cleaning apparatus 22.

As shown in FIG. 2 and FIG. 3, the air passage body 35 is shaped like a box fixedly installed on a plate 41. An inlet side opening 42 is formed in a lower side surface of the air passage body 35 and connects to a suction duct 43 and is in communication with the suction duct 43. The suction duct 43 is in communication with an opening 47 formed between the plate 41 and a plate 44 and having a U-shaped cross section, via a corner passage 46 formed between the upper plate 44 and a lower plate 45 and having a U-shaped cross section. The opening 47 is formed to face the ventilation port 26 in the side door 25. The ventilation port 26 serves as an inlet when cooling air is taken from the outside of the machine room 19 into the air passage body 35.

The corner passage 46 has an open surface on the outside of the corner passage 46 which is closed by a machine cover or a member associated with the machine cover, to form a duct. The suction duct 43 and the corner passage 46 form duct-like air passages 43 and 46. The exhaust gas cleaning apparatus 22 is fixedly installed on the plate 44 using a mounting plate 48.

As shown in FIG. 2, the exhaust line 24 is temporarily drawn out, in the horizontal direction, from the pipe connection portion 28 c of the nitrogen oxide reduction apparatus 28 and then routed obliquely upward. The ejector 51 is provided in the middle of the exhaust line 24. An intake port 52 formed in an outer side surface of the ejector 51 is in communication, via a suction pipe 54, with an outlet side opening 53 formed in an upper end surface portion of the air passage body 35. The ejector 51 utilizes a negative pressure formed around the periphery of an exhaust gas flow to forcibly suck the air in the air passage body 35 through the outlet side opening 53 of the air passage body 35.

As shown in FIG. 2 and FIG. 3, a wall body 55 is provided on the plate 44 and arranged in an L shape so as to enclose the outside of the exhaust gas cleaning apparatus 22. The urea aqueous solution hose 34 is disposed along the wall body 55 using a hook 56 provided on an outer side surface of the wall body 55 and a fitting 57 installed on the plate 44. Moreover, the urea aqueous solution hose 34 is drawn into the corner passage 46 through a pipe introduction inlet portion 58 cut out in a part of the plate 44, and is then inserted through the suction duct 43 into the air passage body 35 and further connected to the injector 29.

Wiring in the air passage body 35 connected to the control boxes 30A and 30B of the NOx sensor 30 is connected, via the suction duct 43 and the like, to a controller (not shown in the drawings) installed in the machine body 11 to control the liquid reducing agent pump 33.

Now, the effects of the embodiment shown in FIG. 1 to FIG. 4 will be described.

The reducing agent supply apparatus 31 pumps up the urea aqueous solution in the liquid reducing agent tank 32 in the storage box 16 using the liquid reducing agent pump 33 and feeds the urea aqueous solution to the exhaust gas cleaning apparatus 22 in the machine room 19 through the urea aqueous solution hose 34. The injector 29 then injects the urea aqueous solution into the pipe 28 a connected to an upstream side of the nitrogen oxide reduction apparatus 28.

At this time, the wall body 55, the corner passage 46, the suction duct 43, and the air passage body 35 function as a heat shielding structure that blocks heat radiated by the exhaust gas cleaning apparatus 22 to protect the urea aqueous solution hose 34 from the heat. Furthermore, the ejector 51 provided in the exhaust line 24 utilizes a negative pressure formed around the periphery of the exhaust gas flow to suck the air in the air passage body 35 into the exhaust gas flow in the exhaust line 24 through the outlet side opening 53 of the air passage body 35, allowing the air to be forcibly discharged to the outside. Thus, cool outside air outside the machine body 11 can be sucked into the air passage body 35 through the ventilation port 26, serving as an outside air intake port of the side door 25, via the opening 47, the corner passage 46, and the suction duct 43.

Thus, while the engine 21 is in operation, the air passage body 35 is internally cooled by the cool outside air, enabling cooling of the urea aqueous solution in the urea aqueous solution hose 34 fitted in the air passage body 35, the NOx sensor 30, and the injector 29.

Thus, the inlet side opening 42 of the air passage body 35 is in communication with the ventilation port 26 outside the machine room, and the ejector 51 provided in the exhaust line 24 utilizes the negative pressure formed around the periphery of the exhaust gas flow to suck the air in the air passage body 35 into the exhaust gas flow in the exhaust line 24 through the outlet side opening 53 of the air passage body 35, allowing the air to be forcibly discharged to the outside. Thus, while the engine 21 is being driven to discharge the exhaust gas, the outside air is constantly introduced into the air passage body 35 to enable efficient cooling of the urea aqueous solution in the urea aqueous solution hose 34, the NOx sensor 30, and the injector 29, which are exposed to the elevated temperature of the exhaust gas cleaning apparatus 22. Consequently, a cooling effect can be exerted using a low-cost duct structure without the need for a special cooling water line or pump. Furthermore, the air passage body 35 may be installed which locally surrounds a part of the urea aqueous solution hose 34, a part of the NOx sensor 30, and apart of the injector 29, that is, the cooling target area, allowing space to be conserved.

Furthermore, inexpensive cooling means for the working machine 10 that performs operations at a fixed location can be provided which means allows efficient cooling of the urea aqueous solution in the urea aqueous solution hose 34, the NOx sensor 30, and the injector 29, which are exposed to the elevated temperature of the exhaust gas cleaning apparatus 22.

The air passage body 35 is not limited to the box-like shape shown in FIG. 2 and FIG. 3. A part of the air passage body 35 from the inlet side opening 42 to the outlet side opening 53 may be shaped like a duct so that the part of the urea aqueous solution hose 34 which is exposed to elevated temperatures, the NOx sensor 30, and a part of the injector 29 can be arranged in the duct. This structure exerts similar effects.

Furthermore, the air passage body 35 allows cooling of the urea aqueous solution in the urea aqueous solution hose 34, the NOx sensor 30, and the injector 29. However, the air passage body 35 may be installed so as to surround one or two of the following: apart of the urea aqueous solution hose 34, apart of the NOx sensor 30, and a part of the injector 29 to allow the one or two to be cooled using cooling air externally obtained.

INDUSTRIAL APPLICABILITY

The present invention is available for manufactures involved in manufacture of a machine body and a working machine characterized by a cooling structure of an exhaust gas cleaning apparatus.

EXPLANATION OF REFERENCE NUMERALS

10 Working machine

11 Machine body

14 Working apparatus

19 Machine room

21 Engine

22 Exhaust gas cleaning apparatus

24 Exhaust line

26 Ventilation port as outside air intake port

29 Injector

30 NOx sensor as nitrogen oxide sensor

31 Reducing agent supply apparatus

34 Urea aqueous solution hose as reducing agent supply pipe

35 Air passage body

42 Inlet side opening

51 Ejector

53 Outlet side opening 

1. A machine body comprising: a machine room; an engine installed in the machine room; an exhaust line through which exhaust gas from the engine is discharged; an exhaust gas cleaning apparatus provided in the exhaust line to execute a reducing process on nitrogen oxide in exhaust gas; and a reducing agent supply apparatus that supplies a liquid reducing agent to the exhaust gas cleaning apparatus through a reducing agent supply pipe, wherein the exhaust gas cleaning apparatus includes: an injector that injects the liquid reducing agent supplied by the reducing agent supply apparatus through the reducing agent supply pipe; a nitrogen oxide sensor that detects a concentration of the nitrogen oxide in the exhaust gas; an air passage body installed so as to surround at least one of a part of the reducing agent supply pipe, a part of the nitrogen oxide sensor, and a part of the injector to allow at least one of the liquid reducing agent in the reducing agent supply pipe, the nitrogen oxide sensor, and the injector to be cooled using cooling air taken from an outside of the machine room, the air passage body including an inlet side opening and an outlet side opening; an outside air intake port which communicates with the inlet side opening of the air passage body and which opens to the outside of the machine room; and an ejector provided in the exhaust line to forcibly discharge air in the air passage body through the outlet side opening of the air passage body by utilizing a negative pressure formed around an exhaust gas flow.
 2. A working machine comprising: the machine body according to claim 1; and a working apparatus mounted on the machine body. 